Issue 788083  has been merged into this issue.

What chromebook are you reproducing this issue on?
Go to chrome://version in your browser and paste the platform field. 

Hello!
This bug is receiving this notice because there has been no acknowledgment of its existence in quite a bit of time
- If you are currently working on this bug, please provide an update.
- If you are currently affected by this bug, please update with your current symptoms and relevant logs.

If there has been no updates provided by EOD Wednesday, 12/12/18 (5pm EST), this bug will be archived and can be re-opened at any time deemed necessary.

Thank you!

IMHO, this works as expected. 

Since the user has disconnected the keyboard manually at step 4, the system respects the user's decision by not reconnecting the device automatically. If the user would like to reconnect, the user needs to click the paired device on the settings page to reconnect manually. No PIN code would be requested in this case. It would just reconnect.

If a user would like the keyboard to reconnect automatically, the user has a few choices
(1) Turn off the keyboard. When turning on the keyboard again, the keyboard would reconnect automatically.
(2) Just leave the keyboard idle for a while. The keyboard would disconnect later to save power. After clicking on a key, the keyboard would resume and reconnect automatically.
(3) Let the system suspend by closing the chromebook. To reconnect, just click a key on the keyboard after the system is resumed by opening the lid. The keyboard should reconnect automatically.

Let's WontFix?

Due to lack of action this bug has been Archived. If work is still being done on this issue or you are still experiencing this issue please feel free to re-open with the appropriate information.